V4L/DVB (3931): Vivi.c: possible cleanups

This patch contains the following possible cleanup:
- make needlessly global functions static
- remove unused #ifndef kzalloc kzalloc() #define
- remove inline's from functions

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>